<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>CSS样式基础</title>
  <!-- 外部样式 -->
  <link rel="stylesheet" href="./index.css">
  <style type="text/css">
  /* 内部样式 */
    div{
      background-color: blue;
    }
  </style>
</head>
<body>
  <div style="background-color: red;"></div>
</body>
</html>